Towards realistic characterisation of chemical reactors: An in-depth analysis of catalytic particle beds produced by sieving

Optimization of large-scale fixed particle bed catalytic reactors requires extensive insight into the multi-scale bed structure, even down to the micrometre scale. Theoretical studies of chemical reactors provide a time- and cost-effective means to supporting the optimisation process. However, they rely on simplified assumptions for the particles, e.g. homogeneous perfect spheres. In practise, the preparation of catalytic particles cannot attain this level of uniformity. Typical preparation techniques, such as sieving, are conducted with the aim of obtaining particle size distributions within a pre-defined range, governed by the sizes of the sieves. However, such methods offer limited control in the actual particle sizes and shapes. This paper evaluates the impact of sieving on the resulting particles and overall structural morphology of catalytic beds. The bed structure is quantified using micro-focus computed tomography (µ-CT), enabling the non-destructive examination and analysis of over 150 thousand particles, in terms of particle size, shape, uniformity, and interparticle porosity. Furthermore, the chemical performance of the resulting beds is compared. The detailed characterisation achieved paves the way for the evolution of more rigorous computational models coupling intricate, localised hydrodynamics with realistic chemical processes. Validation of such models at the lab-scale will accelerate the development of more accurate large-scale models.